1. Field of the Invention
The invention relates to RF smart labels and sensors, software and processes particularly for monitoring and analyzing the shelf life of a perishable product.
2. Description of the Related Art
Perishable products, such as chilled and minimally processed food products, vaccines, pharmaceuticals, blood, film, chemicals, adhesives, paint, munitions, batteries, soft drinks, beer, cosmetics and many other products, each have a unique shelf life. Product quality is affected by a number of factors that may be physical, chemical or biological in nature, and that act together in often complex and interconnected ways. However, temperature is usually the predominant factor determining the longevity of quality. It is desired to accurately monitor and analyze this “shelf life” or perishability.
Today the date stamp, whether it is “use-by”, “sell-by” or “closed” (special number on the product which only the product manufacturer understands), is the product producer's rule of thumb or “best guess” of the quality of a product—in terms of taste, texture, aroma, appearance and more. When a product is used or eaten after this date, its quality may be less than what the product manufacturer wants you, its customer, to experience.
Product dates are based on the product manufacturer's best assessment of the temperature to be experienced by the perishable, from the time it leaves the plant until it is acquired by the user. Because temperature is often different from what was predicted, the date alone is not always an accurate representation of shelf life. If a product is properly transported and stored, it can last much longer than the date. Conversely, if the temperature is higher than predicted, the product deteriorates more quickly in relation to temperature. A “dead date” is simply typically ascribed to a product, as if only time played a role in the spoilage of a product, or as if the product spoilage rate was independent of temperature. However, it is well known that many products spoil far more slowly when they are refrigerated, than when they are stored at room temperature. Once a “dead date” is applied conventionally to a product, it cannot be changed to reflect what has happened to the product.
In a product supply chain, the use of RF transponders (also known as RFID or radio frequency identification) has grown in use as a result of the establishment of RF frequency and data format standardization by ISO and EPCglobal for tracking and tracing of products. Additionally the wide use of Bluetooth and Zigbee (other RF-based communication interfaces) has resulted in additional inexpensive RF input and output options for active monitoring of products. At the same time, advances in digital sensing have made possible low cost sensors for monitoring certain conditions of products, especially temperature, humidity, vibration and shelf life (integration of time and temperature).